I don't know if its really true (never saw it), or if there were further problems, but when I was a kid in the fifties, it was said that a guy had built a bomb shelter under his driveway. He apparently ripped up the driveway, installed the shelter, covered it up and relaid the driveway over it.

Wouldn't the weight of a car (or cars) rolling and sitting on top of it tend to cause problems?

Anyway, I'm just throwing this old story out there.

Sue